var fs=require("fs");
var data='菜鸟教程官网地址：www.runoob.com';

var writerStream=fs.createWriteStream('output.txt');
writerStream.write(data,'UTF-8');

writerStream.end();

writerStream.on('finish',function(){
    console.log("写入完成.")
});

writerStream.on('error',function(err){
    console.log(err.stack);
});